[[quoteright:300:[[WesternAnimation/JusticeLeagueDoom http://static.tvtropes.org/pmwiki/pub/images/9bd6085cdca8331858bcf2801cbd064d.jpg]]]]
[[caption-width-right:300:Nothing says true friendship than to give your buddy the only thing that can kill you. [[note]] But let's be honest, Franchise/{{Batman}} [[CrazyPrepared already had kryptonite.]] [[/note]] ]]

-> '''Franchise/{{Superman}}:''' I have many enemies who have tried to control me. And I live in fear that someday, they might succeed. If that should ever happen -- if I should ever lose control -- there would only be one sure way to stop me.\\
'''Franchise/{{Batman}}:''' Do you realize what you're asking?\\
'''Superman:''' I do. I want the means to stop me in the hands of a man I can trust with my life.
-->-- ''ComicBook/TheDeathOfSuperman'' (flashback)

In an optimistic setting, this device is from a character who is aware of their KryptoniteFactor and puts the means to stop them in the hands of another (usually, in case they're {{brainwashed}} or [[FaceHeelTurn go evil somehow]]). This usually implies a bond of trust since the receiver often has mixed feelings about the idea and the giver has to insist. This is also a show of good faith to a skeptic so he will allow the hero to operate in a legal grey area.

This trope is named after the ring Superman gave Batman in case he ever got out of control.

Compare BetrayalInsurance where the "stopping" character came up with it on their own; exactly how extensive this planning comes off can seriously affect the relationship depending on how betrayed the other feels.


[[AC:Comic Books]]
* Franchise/XMen:
** Professor Xavier also had the "Xavier Protocols", a set of plans on how to stop the X-Men. Xavier himself is the subject of the first entry, which includes blueprints for a [[PowerNullifier telepathy-blocking battlesuit]]. However, these have rarely been mentioned since they were first introduced.
** In ''ComicBook/{{Wolverine}}: Origins'' Wolverine gives ComicBook/{{Cyclops}} his magical sword, which is capable of slicing through his adamantium skeleton and negating his healing abilities, in case he gets captured and brainwashed. Of course his son gains it later. Though at least Wolverine was able to use it to kill Sabertooth first (not that ''that'' stuck even a whole year).
* In Frank Miller's dark, [[TwentyMinutesIntoTheFuture near-future]] miniseries ''ComicBook/BatmanTheDarkKnightReturns'', Batman [[strike: actually uses his Kryptonite Ring (the cynical version)]] has ComicBook/GreenArrow shoot Superman with a [[TrickArrow Kryptonite arrow]] to beat the crap out of Superman. This inspired the writers to have the canon Superman give Batman a Kryptonite Ring (the idealistic version).
** The quote is a slightly truncated version from the storyline Batman got the ring, "Dark Knight Over Metropolis". In it, Superman and Batman work together to try to figure out why a homeless man was found dead with Lex Luthor's old Kryptonite Ring. Batman ultimately pieces together that the ring was actually in the possession of a woman who became manically determined to prove Clark Kent and Superman were one and the same and was killed by a bunch of random muggers, which lead the homeless man to take the ring. Batman initially kept the ring, but gave it to Superman at the end, only for the Man of Steel to return to Batman and give him the ring, feeling that he could trust Batman with such a dangerous weapon.
** This specific dynamic, Batman holding Kryptonite, appears again and again, especially in the Franchise/DCAnimatedUniverse. During the height of the Cadmus story in ''WesternAnimation/JusticeLeague'', Batman asks Superman what could stop the latter from taking over the world, if he so desired. Supes quips, "There's always that Kryptonite you carry around." Which makes Batman ''snap at him'' for being so flippant about so serious a topic.
** Subverted in Pre-Crisis story ''World's Finest'' #176 in which Batman appears to have Kryptonite gloves, but in reality they are fake. Curiously, before he reveals that they are props, no one -not even ComicBook/{{Supergirl}}- questions why he has something that can kill his best buddy.
** There's also the piece he uses against A.M.A.Z.O. when it copies Superman's powers (and weaknesses.)
--->'''Hawkgirl''': Do you always keep that in your belt?\\
'''Batman''': Call it... insurance. ([[GrapplingHookPistol grapples away]])\\
'''Hawkgirl''': And they call me scary.
** ''WesternAnimation/TheBatman'' has an incredibly cynical version. When Batman got a piece of kryptonite off of Metallo, not only did he keep it, he ''lied about giving it back'' (he gave Supes a fake one and kept the real one). He did it to "get even" with Superman for finding out his identity. However, by the end of the episode, it's the idealistic version, as they have settled their differences, and when Batman offers to give Supes the ''real'' kryptonite, Superman says to keep it. It still goes to show you that Batman really doesn't like anyone being nearly as CrazyPrepared as him.
** This is also inverted by the end of ''WesternAnimation/TheBatman'': Batman gives each member weapons that simulate each WesternAnimation/JusticeLeague member's weaknesses because aliens have invaded and copied their powers. They call him out on being so paranoid, until Superman steps forwards and [[ProperlyParanoid cites the time he was mind controlled in a previous episode]].
** ''ComicBook/SupermanBatman''
*** A story ''combines'' the idealistic and cynical versions: after a long-term mission to destroy all the kryptonite on Earth, Superman saves one piece, which he gives to Batman for emergencies. Batman takes it to a lead-lined room in the deepest area of the Batcave... which is ''already'' filled with multiple kinds of kryptonite!
*** In ''ComicBook/TheSupergirlFromKrypton'' Batman uses a chunk of Green-K to knock [[Comicbook/{{Supergirl}} Kara]] out and bring her to the Batcave. Later, [[spoiler:Superman]] of all people uses a kryptonite ring to [[spoiler:knock a brainwashed Kara out]].
** In ''ComicBook/ElseworldsFinestSupergirlAndBatgirl'', ''ComicBook/LexLuthor'' has a Kryptonite ring that he plans to use against ''ComicBook/{{Supergirl}}''... until ''ComicBook/{{Batgirl}}'' steals it from him and takes it to a lead-lined vault, saying "I see it as insurance... which I hope I never need to use."
** The trope is referenced, as always in combination with CrazyPrepared, when in the first episode of ''WesternAnimation/BatmanTheBraveAndTheBold'', Jaime Reyes asks his friend who he thinks would win: Batman (no kryptonite) or mind-controlled Superman. He then informs his friend, who answered "Superman", that it was a trick question: "Batman ''always'' has kryptonite".
** The ComicBook/New52 version is idealistic and ''reciprocal'', as Batman includes himself in the countermeasures list, trusting Superman to stop him if necessary.
** In ''Comicbook/WarWorld'', the Martians prepared a cluster of miniature missiles armed with Kryptonite in case that Superman tried to seize the device that controls the eponymous super-weapon and they were tasked with guarding.
** To a lesser extent, the ''Comicbook/{{Shazam}}!'' Captain Marvel is employed occasionally as the one superhero tough enough to take on a controlled Superman if necessary. Or rather, he's tough enough to stall Supes in a fistfight long enough to call his magical lightning enough times to knock out his Kryptonian foe[[note]]Most forms of magic are able to bypass Superman's NighInvulnerability and damage him just like a de-powered kryptonian. As for how the Kryptonite Ring trope comes into play: Superman isn't going to tell just anyone this fun little fact, but he can usually trust the goody-two-shoes Captain marvel[[/note]]. Altough, at least in [[ComicBook/KingdomCome one occasion]], it was ''Captain Marvel'' the brainwashed one, not Superman.
** From the ComicBook/LegionOfSuperHeroes example above: General Zod's son, Drax, stole Brainiac 5's kryptonite and tries to use it on Supes, but Superman kicked him through a conveniently placed PhantomZone portal, ''before he could even open the lead container''.
** Pre-ComicBook/{{Crisis|on Infinite Earths}}, Superman's heat vision could melt kryptonite, rendering it useless somehow. This usually worked only on small pieces, though; in one instance a large meteor of the stuff fell next to him and incapacitated him before he could melt it.
** Referenced in ''ComicBook/KingdomCome'', but it's noted that Superman has grown more and more powerful as he's aged and absorbed more solar energy, and Kryptonite doesn't really work on him anymore.
** ''ComicBook/InfiniteCrisis'' subverts this when Batman tries to use his Kryptonite ring on Superman of Earth-Two, which has no effect, as explained in explication.
--->'''Kal-L''': "But the Kryptonite here isn't from my Krypton. It doesn't hurt me... physically, at least. But that ring [...] represents the paranoia and mistrust that will destroy your world if you let it."
** The video game ''VideoGame/InjusticeGodsAmongUs'' takes this a step further; [[spoiler: In Superman's ending, it's revealed that the Regime-Superman's ease at conquering the world only made him even more terrified of what could happen if he ever lost control of himself. He makes sure this doesn't happen by having a Kryptonite ''bomb'' implanted by his heart, which will instantly kill him should this happen. The other members of the Justice League all take turns carrying the detonator for it. Except for Batman, who was denied a shift.]]
* In the BackStory of ''ComicBook/ExMachina'', The Great Machine (now the mayor of New York City) gave his two {{Secret Keeper}}s devices to cancel-out his ability to talk to machines. As was his habit, he explicitly referenced the Superman mythos as he did so. As we later learn [[spoiler:it's just junk made out of old garage door openers and doesn't affect his powers at all. He lied and gave them to his {{Secret Keeper}}s so that, if they ever betrayed him or were forced to turn against him, their plotting would depend on something that doesn't work. (Though a major plot hole is that it did work in the first story arc.)]].
* There's no actual power-cancelling device, but ''Comicbook/AvatarTheLastAirbenderThePromise'' begins with Zuko asking Aang to kill him if he ever starts following in his father's footsteps. This comes directly after the series finale, in which Aang found a way around executing Zuko's dad (who is pretty much the most despicable man alive). He's not exactly thrilled, but Zuko insists he promise. Cut to a year later when {{Realpolitik}} has forced Zuko to enforce a slew of distinctive Ozai-like decisions. Cue drama.

* In ''Series/BuffyTheVampireSlayer''/''ComicBook/{{Supergirl}}'' crossover ''Fanfic/TheVampireOfSteel'', Supergirl lends her friends a chunk of Kryptonite in the event that things go South during the FinalBattle.

* In ''Film/TheDarkKnight'', Batman gives Lucius Fox sole control over [[spoiler:the cell phone sonar system and the ability to destroy it so that Fox will trust him to use it only against the Joker. Though Fox didn't actually find out about the second part (cryptic instructions on how to "turn it off") until the Joker was caught.]]
* In ''Film/AvengersAgeOfUltron'', Franchise/IronMan and Bruce Banner discuss on how they developed "Veronica", the Hulkbuster armor, as a "[[GodzillaThreshold last resort]]" to stop the Hulk. So when it needs to be employed, it serves this function perfectly.

* In ''Series/StarTrekTheNextGeneration'', there are various methods created to deal with Data to control him in case of possession or other matters. There is an off switch located on his spine that only a few know about, and some AppliedPhlebotinum to disable him for extended periods.
* In ''Series/TerminatorTheSarahConnorChronicles'', Cameron installs a bomb in her head and gives John the detonator, in case she ever becomes a threat to him. She has good reason to worry about this, because it's happened to her before and nobody (not even the Teminators themselves) knows what causes a reprogrammed Terminator to suddenly revert to its default programming.
* In ''Series/{{Smallville}}'':
** Oliver Queen kills ComicBook/LexLuthor and takes his kryptonite ring, confirming his role as Smallville's Batman. (Well, except for the ThouShaltNotKill thing.)
** The Kents are also known to keep pieces of green kryptonite around. It was first used to counteract red kryptonite, but later his parents and [[SecretKeeper Chloe]] [[PlatonicLifePartners Sullivan]] uses it a lot to stop him whenever he is mind controlled (Chloe saves Lex from Clark in ''Hypnotic''), possessed (Jonathan saves Chloe from Dawn possessing Clark in ''Spirit'') or is otherwise not in his right mind (Chloe saves Jonathan from Clark when he is made paranoid by silver kryptonite in ''Splinter'').
** DoubleSubverted in season nine. Clark gets mad at Chloe when he discovers she's been stockpiling kryptonite weapons. Then it turns out she was doing it in case he had to fight Zod and the Kandorians.
* ''Series/KamenRiderBuild'': [[ScienceHero Sento]] created an anti-hazard switch that he handed to [[FamilyOfChoice Misora]]. She was supposed to use it in case he lost control of [[SuperpoweredEvilSide Hazard]] form and there wasn't anyone to stop him. He told her that it will just knock him out of [[HenshinHero transformation]]. She correctly deduces that this is not all and manages to make tell her the whole thing. It will also destroy the Build Driver and [[DrivenToSuicide kill]] him. She is [[WhatTheHellHero very]], ''[[ANgerBornOfWorry very]]'' mad at him for making her promise she will murder him if the need arises.
* In ''Series/TheFlash2014'', [[TheSmartGuy Cisco]] creates the [[FreezeRay Cold Gun]] in case Barry turns out to be dangerous, like the other [[DifferentlyPoweredIndividual metahumans]]. Unfortunately, it gets stolen and later gets into the hands of the future Captain Cold. Both Wells and Barry tear Cisco a new one for making the gun.

* It is eventually revealed in ''VideoGame/FinalFantasyVIII'' that [[spoiler:Edea had feared being taken over by an evil sorceress, and with her husband created a fighting force to oppose her in that event, which has already come to pass by the game's beginning.]]
* The second half of ''VideoGame/TheLegendOfZeldaPhantomHourglass'' involves Link trying to forge the Phantom Sword, the only weapon capable of destroying the otherwise-invulnerable Phantom enemies [[spoiler:as well as Bellum, the BigBad of the game.]]

* The [[Roleplay/GlobalGuardiansPBEMUniverse Global Guardians]] keep a locked file in their computer database called the Code Red Omega Scenario. It is a tactical plan to take down each and every member of the Guardians, if it ever became necessary to take them all down.
* Literature/WhateleyUniverse: As of "Ayla and the Mad Scientist" we now know Phase has at least several plans to take down every one of his teammates. And a bunch to take down himself. And his teammates know his 'official' weakness in the school records is a fake. He wrote up a list of real ways to stop himself and gave it to Lancer.

* ''WesternAnimation/SilverHawks'': Each of the SilverHawks has an emergency off-switch to be used if any of them went berserk for unforseen reasons.

* Some people have said that the second amendment of the American constitution, the right to bear arms, is there partly in case of the government being taken over by an oppressive tyrant of some kind. In this event the people would be able to overthrow the regime because they would all be equipped with guns. This can be seen as the founding fathers giving future generations of citizens a kryptonite ring. There is substantial disagreement over whether this was a true intention as well as just what the actual effectiveness of it is in the 21st Century given the now extremely broad gap between civilian and military weaponry. [[RuleOfCautiousEditingJudgement Which is as much as should be said about the matter]].